Trembath Basin Geotechnical Investigation Project. No. 6D8532, CP#19-32
- SCH Number
- Lead Agency
- Contra Costa County
- Document Title
- Trembath Basin Geotechnical Investigation Project. No. 6D8532, CP#19-32
- Document Type
- NOE - Notice of Exemption
- Project Applicant
- Contra Costa County Flood Control District
- Document Description
- Contra Costa County Flood Control and Water Conservation District (District) proposes to conduct supplemental geotechnical investigations required to support the geotechnical analyses and detailed design for the proposed Trembath Detention Basin. The geotechnical investigation is planned for fall 2019. The geotechnical investigation includes subsurface exploration that includes four rotary wash borings, one of which will receive a vibrating wire piezometer, seven standard cone penetration tests (CPT) and one seismic CPT. A minimum of three test pits will also be performed within the proposed embankment footprint at locations to be determined after geologic field mapping, test borings, and CPTs have been completed. Test borings will be drilled using track or truck-mounted drilling equipment. CPTs will be advanced using track-mounted CPT equipment. Test pits will be excavated using either a track-mounted excavator or backhoe. Drilling fluids will be circulated in tubs and portable tanks at the drill site. When the fluids need to be disposed of, they will be contained in tanks, drums, or bins and stored in a secure area on site until the end of exploration activities. The tanks/drums/bins then will be transported and disposed of at a landfill. The subsurface exploration program will be used to characterize the subsurface conditions for the planned project elements and to obtain samples for laboratory testing. The boreholes will be backfilled with bentonite, and soil within the upper two feet.
- Contra Costa
- Other Location Info
- Trembath Street and Yellowstone Drive, east of Hillcrest Avenue between East 18th Street to the north and Highway 4 to the south
Notice of Exemption
- Exempt Status
- Categorical Exemption
- Type, Section or Code
- Reasons for Exemption
- The geotechnical investigation consists of data collection that does not result in a serious or major disturbance to an environmental resource pursuant to section 15306 of the State CEQA Guidelines.
- Notice of Exemption
- 2020010499_Trembath Basin Geotechnical PDF 1988 K
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